In the original vampire story, Brahm Stoker's Dracula, daylight turned Dracula into a 'low-powered vampire'. Basically, he couldn't acccess most of his abilities. The concept of vamires bursting into flame and such came with the advent of cinema, as it was found to be more exciting. Sparkles were never my greatest concern anyway. I was more concerned when, upon investigating the 'romance', I found many signs of an abusive relationship in the making. Watching her while she sleeps, following her around, other stuff I can't recall, but isn't normal or healthy. All of my information is second hand, as I couldn't be arsed to read the novel, so I may be wrong.